Anyone experience this with their automatic transmission?

[Lb445]

Hey all, I just bought my first jeep wrangler (2004 sport, 4.0 I6, automatic) and brought it to get fixed up straight away (all new suspension components since everything was worn, new radiator and valve cover gasket, diff service, oil + coolant change, wheel alignment) and when I finally got to drive around in it as I'm changing gears I notice weird noises for like 2 seconds when it is in the other gear. Sounds like metal being scratched on pavement. When I'm driving in reverse it makes a grinding sound. And it even has trouble getting into the right gear even when I put it there for example I had it in park but nothing happened when I put my key in the ignition to I moved the gear shifter a smidge up more and finally I get it to turn on. So these lead me to believe there is a trans issue however my mechanic said it's fine? I was wondering If anyone here has experience with this and could give me their opinion

 

[AndyG]

Check the fluid and drop the pan and check for metal. Soon.